Locking prevention means for gripper units



LOCKING PREVENTION MEANS FOR GRIPPER UNITS Filed Dec. 14, 1961 2 Sheets-Sheet 1 INVENTOR JOHN M. ERNST ATTOR EY United States Patent Ofi Fice3,138,379 Patented June 23, 1964 3,138,379 LUCKING PREVENTION MEANS FORGRIPPER UNITS John M. Ernst, Shelby, Ohio, assignor to American giachine& Foundry Company, a corporation of New ersey Filed Dec. 14, 1961, Ser.No. 159,225 14 Claims. (Cl. 273-43) This invention relates to bowlingpin respotting mechanisms of bowling pin spotting machines forautomatically spotting and respotting bowling pins on the playing bed ofa bowling alley.

The present invention is an improvement over bowling pin spottingmachines of a type similar to that disclosed in U.S. Patent2,781,195-Holloway et al. In such prior art machines, the respottingunits are supported on a spotting-respotting table which is raised andlowered relative to the pin deck of a bowling alley for respottingstanding pins on the pin deck. Normally, such machines are operated sothat after the first ball of a frame has been thrown and there remainsat least one standing pin on the pin deck, the table is lowered and eachrespotting unit, which is provided with a pair of grippers that grip thehead of a standing pin, picks up such pin upon subsequent upwardmovement of the table. Then, a pin sweep clears the alley of deadwoodand the table is lowered so that the respotting units respot thestanding pins on the pin deck. After the last ball of a frame has beenthrown, the table is not lowered and the pin sweep sweeps the deadwoodand standing pins, if any, from the alley into the pit.

Some of these prior art machines are also equipped with annunciatorsthat are actuated by the respotting units to indicate which pins arestanding after the first ball of a frame has been thrown. But, sinceafter the last ball of a frame has been thrown, the table is notlowered, such annunciators are not actuated. Therefore, the player mustrely solely on his ability to be able to correctly identify the numberof pins which are standing.

Furthermore, it occasionally happens during the course of play that aflying pin will strike the prior art respotting units and cause thegrippers to be moved toward each other and locked so that when the tableis subsequently lowered, the locked grippers can engage the top of astanding pin and either damage the pin or the spotting machine. Whereannunciators are also used, the locked grippers improperly indicate thepresence of a standing pin.

Accordingly, one of the objects of this invention is to provide animproved respotting mechanism for an automatic bowling pin spottingmachine.

Another object is to provide a bowling pin spotting machine withimproved means for indicating which pins are standing after each ball ofa frame has been thrown.

Still another object is to provide an improved respotting mechanismwhich cannot be locked in a closed position by a flying pin.

A further object is to provide an improved respotting mechanism, whichincludes a plurality of respotting units and a control system therefor,that is not subject to being actuated by a flying pin and which willindicate the presence and positions of those pins which are standingafter each ball of a frame has'been thrown.

In order that the manner in which these and other objects are attainedin accordance with the invention can be understood in detail, referenceis had to the accompanying drawings, which form a part of thisspecification, and wherein:

FIGURE 1 is a schematic dliagram for a bowling pin spotting machineembodying the invention;

FIGURE 2 is a side elevational view, partly in section, and withportions broken away, of a respotting unit illustrating the unit priorto actuation thereof by a stand ing pin; and

FIGURE 3 is a view similar to FIGURE 2 illustrating the respotting unitwhen a bowling pin is gripped thereby.

Referring now to the drawings, the embodiment there illustrated includesa table T and a plurality of respotting units 1-10 which, except for thelatching mechanism, are similar to those in U.S. Patent2,781,195Holloway et al., to which reference can be had for a moredetailed description.

Respotting units 1-10 are arranged on table T in a triangularrelationship with each unit above the position of a different one of thebowling pins spotted on the pin deck of a lane or alley. Respotting unit1 is above the head of #1 pin, respotting unit 2 is above the #2 pin,etc. The respotting units are similar, so that only one need bedescribed in detail.

With reference to FIGURES 2 and 3, respotting unit 1 is mounted on tableT by a bracket 12 keyed to a shaft 13, the respotting unit comprising aclamping member 14, a pair of grippers 15 and 16, and latch means 17.Clamping member 14 comprises a horizontal clamping pad 18 preferablyformed of resilient material such as sponge rubber, and a rigid supportmember having a lower horizontal plate 19 backing up clamping pad 18 anda vertical portion 20 extending upwardly from plate 19. A pair ofparallel links 21 and 22 are pivotally connected to portion 20 and to adependent portion 23 of bracket 12 and pivotally mount the clampingmember on the table.

Grippers 15 and 16 comprise a pair of opposed gripping jaws 24 and 25 ofa suitable resilient material such as sponge rubber, supported on a pairof gripping jaw support members 26 and 27. These support members, inturn, are supported by a plurality of rollers 28 guided by a horizontaltrack 29 secured to clamping member 14 so that the gripping jaws canmove horizontally toward and away from each other in a plane parallel tothe pin deck and transversely of a standing pin P.

Grippers 15 and 16 move in response to relative movement between table Tand clamping member 14 by means of rollers 30 and 31 received in camtracks 32 and 33 of a frame member 34 supported on a horizontal track 35by a pair of rollers 36. Rollers 30 and 31 are secured to grippers 15and 16, respectively, and track 35 is secured to bracket 12 so that astable T moves relative to clamping member 14, frame member 34 movesrelative to the rollers 30 and 31 and thereby causes rollers 30 and 31to travel along portions of cam tracks 32 and 33. Cam tracks 32 and 33include lower divergent portions and upper parallel vertical portions,the lower portions being operative upon downward movement of table Trelative to the clamping member to move grippers 15 and 16 toward eachother and thereby grip the standingpin causing such movement. Upwardmovement of table T relative to clamping member 14 causes lower portionsof cam track 32 and 33 to move grippers 15 and 16 away from each otherto release the pin gripped thereby. When table T is above that positionat which any of the respotting units can engage a standing pin, clampingmember 14 is gravity biased, due to its own weight and to the weight ofthe parts connected to it, to the position shown in FIGURE 2 whereinrollers 30 and 31 engage the lower end of cam tracks 32 and 33.

In accordance with the illustrated embodiment, it is contemplated thatthe movement of the table T be controlled by a system similar to thatdisclosed in US. Walsh Patent 2,974,955. For a normal two-ball frametype of game, such movement is as follows. After the first ball of aframe has been thrown, table T is moved through a respotting cycle whichcomprises lowering and raising the table to enable standing pins to bepicked up and, after a the alley has been cleared of deadwood, loweringand raising the table to respot the pins on the pin deck. After thesecond ball has been thrown, table T is moved sequentially through adetecting cycle and through a spotting cycle. During the detectingcycle, table T is lowered and raised to detect standing pins. Then,after the alley has been cleared of such pins and any deadwood, thetable is lowered and raised through a spotting cycle to spot a completeset of pins on the pin deck.

Latch means 17 comprises a latch member 37 rigidly mounted on portion ofclamping member 14 for movement therewith, and a latch hook 38 pivotallymounted on bracket 12 for vertical movement therewith and for pivotalmovement relative thereto. This pivotal movement is caused by a solenoid39 and a restoring spring 40 upon energization and de-energization ofthe solenoid. Solenoid 39 is supported in a vertical position on bracket12 and has a vertically movable plunger 41. Latch hook 38 is in the formof a bell crank lever and has its upper end connected to plunger 41 sothat vertical movement of plunger 41 causes the lower or free end oflatch hook 38 to move through a small arc.

Latch book 38 is movable alternately between an inoperative position(FIGURE 2), and an operative position (FIGURE 3). When solenoid 39 isenergized, the latch hook is moved to its operative position. Whensolenoid 39 is de-energized, the latch hook is movable to itsinoperative position.

Near the beginning of the respotting cycle, solenoid 39 is energized andlatch hook 38 is moved to its operative position wherein the free endthereof can travel along a vertical path intersecting the free end oflatch member 37. If there is a standing pin beneath clamping member 14,the lowering of table T causes latch hook 38 to earn over latch member37 whereby subsequent upward movement of table T moves latch hook 38into locking engagement with latch member 37, as illustrated in FIGURE3.

After the grippers are locked, solenoid 39 is de-energized but, becausethe free ends are hooked, latch hook 38 and latch member 37 remainlocked. When the table is lowered to respot pin P on the alley, the baseof the pin engages the pin deck and causes latch hook 38 to movedownwardly a small distance relative to latch member 37. Such movementdisengages latch book 38 and allows spring 40 to move the latch hook toits inoperative position as shown in FlGURE 2, whereby subsequent upwardmovement of table T disengages grippers 15 and 16 and respots pin P onthe pin deck.

The locking and unlocking of latch hook 38 and latch member 37 might bebetter understood in view of the following. With reference to FIGURE 3,line 69 represents the position of clamping member 14, using the upperedge of track 29 as a reference, when clamping member 14 clamps pin Pagainst the pin deck. Line 71 represents the lowest position of table Tduring the respotting cycle and line 70 represents the position of tableT when the latch means 17 is locked, lines 70 and 71 using the loweredge of track as a reference.

During the respotting cycle, table T is lowered into and raised fromposition 71 to allow any standing pins to be picked up. A standing pin Parrests downward movement of clamping member 14 at 69 and allows latchhook 78 to cam over latch member 37 whereby subsequent upward movementof table T from position 71 to position 70 moves latch hook 38 intolocking engagement with latch member 37. During movement of table Tbetween positions 70 and 71, pin P remains in engagement with the pindeck. Consequently, when table T is lowered to respot pin P on the pindeck and moves downwardly from position 70 to position 71, latch hook 38moves downwardly and, because solenoid 39 is then deenergized,disengages latch member 37 in the manner previously described.

Mounted above cross bar 42 of portion 23 is a singlepole, single-throw,normally-closed switch 43 having an exposed button that is actuated by alever 44 connected to one end of a spring 45. This spring has its otherend connected to link 21 and is operative to prevent damage to switch 43caused by over-travel of lever 44. When respotting unit 1 does notengage a standing pin, lever 44 actuates and opens switch 43, asillustrated in FIG- URE 2. However, when a standing pin causes clampingmember 14 to move upwardly relative to table T, lever 44 is pivoted awayfrom switch 43 and thereby closes the switch.

Referring now to FIG. 1, the illustrated embodiment also includes anannunciator A provided with a plurality of lamps L1-L10 arranged in atriangular relationship corresponding to the positions of pins spottedupon the pin deck of an alley, the annunciator being exposed for view bya player so that illumination of the lamps indicates which pins arestanding. That is, when lamp L1 is illuminated, it indicates that the #1pin is standing, when lamp L2 is illuminated, it indicates that the #2pin is standing, etc.

With reference to respotting unit 1, each respotting unit is associatedwith a double-pole, single-throw, normally open electromagnetic relaycomprising a coil 47, a first set of contacts 48 and a second set ofcontacts 49. Power for operation of the electrical components of theillustrated embodiment is derived from a pair of power lines and 51adapted to be connected to a suitable source of power (not shown).Switch 43 is connected in series with coil 47 across lines 50 and 51.Contacts 49 are connected across the power lines 50 and 51 in serieswith lamp L1 so that operation of contacts 49 controls the operation oflamp L1.

The illustrated embodiment also includes a master control systemcomprising a pair of switches 52 and 53 actuated by rotary earns 54 and55 driven by a timing motor 56, and a pair of switches 57 and 58actuated by rotary cams 59 and 60 driven by a timing motor 61. Switch 57is connected in series with motor 56 for controlling the operationthereof, whereas the operation of motor 61 is controlled by adouble-pole, single-throw, normally open relay having a coil 62 and apair of sets of contacts 63 and 64, motor 61 being in series withcontacts 63.

The timing motors are arranged so that, after each ball of a normaltwo-ball frame has been thrown, motor 61 rotates earns 59 and 60 throughone revolution (360) and motor 56 rotates cams 54 and 55 throughone-half revolution (180).

A ball actuated pit switch 65 is connected in parallel with a manualstrike switch 66 and with a series circuit comprising switch 58connected in series with contact 64, the resultant circuit beingconnected in series with coil 62 across lines 50 and 51.

Switch 52 is connected in series with contacts 48 of each respottingunit so that, within each unit, the series circuit of switch 52 andcontacts 48 is in parallel with switch 43 of that particular unit.Switch 53 is connected in series with each solenoid 39 of respottingunits 1-10 so that switch 53 controls operation of all of the solenoidsand of the latch hooks.

The master control system operates in a timed relationship with thecontrol system for table T so that the illustrated embodiment operatesin the following manner. The first ball of a frame momentarily closespit switch 65 and thereby allows current to flow through coil 62 toclose contacts 63 and 64. The closing of contacts 63 energizes motor 61and thereby rotates earns 59 and 60. Cam 60 is arranged so that, uponinitial rotation thereof, switch 58 closes and establishes a holdcircuit for energizing coil 62. At the end of one revolution, cam 60opens switch 58 and thereby de-energizes coil 62, cansing contacts 63and 64 to open. As cam 59 rotates, it closes switch 57 at the beginningof each revolution and opens switch 57 at the end of each revolution,and thereby operates motor 56 only so long as switch 57 remains closed,that is, for the period during which motor 61 rotates cam 59 through onerevolution.

As motor 56 rotates cams 54 and 55 from their start positionsillustrated in FIG. 1, switches 52 and 53 are closed. The closing ofswitch 53 actuates all of solenoids 39 and thereby pivots all of latchhooks 38 from their inoperative positions to their operative positions.This is done before any of the respotting units initially engages anystanding pin. Switch 53 is opened and solenoid 39 is de-energized afterthe latch hooks 38 lock with latch members 37, whereby standing pins arepicked up and respotted in the manner previously described.

Cam 55 is arranged so that switch 53 is open at all times other thanabove. Consequently, during other portions of the cycles and during thecourse of play, the latch members 37 cannot be engaged by and lockedwith the latch hooks 38.

Actuation of motor 56 rotates cam 54, which closes switch 52 throughouta portion of each half revolution or cam 54. When switch 52 is closed, apotential is applied across contacts 48 so that, if a standing pin isbeneath the respotting unit associated with such contacts, the closingof switch 43 in response to the presence of such pin will energize coil47 and thereby close contacts 48 and 49 to establish, through contacts48, a hold circuit for coil 47. Cam 54 is arranged to close switch 52 sothat this hold circuit maintains the lamp associated with it illuminatedfor a suflicient period of time to enable a player to visually observevia annunciator A which pins are standing.

The second ball of a frame closes switch 65 and thereby energizes coil62 and closes contacts 63 and 64 so that motor 61 rotates through asecond complete revolution. During rotation of motor 61 through thesecond revolution of each frame, motor 56 rotates earns 54 and 55through the second half of one revolution, during which time switch 53is open and switch 52 is closed, to detect and indicate which, if any,pins are standing, in a manner similar to that described with referenceto the first ball. Since switch 53 remains open, solenoid 39 remainsde-energized. Therefore, respotting units 1 are inoperative and anystanding pins are swept into the pit of the alley by sweep means (notshown).

In the event a strike is made by the first ball, switch 66 is actuatedmanually to produce an artificial second ball cycle whereby motor 56rotates cams 54 and 55 through 180 to their normal start positions tocondition the system for the next frame.

If, during the course of play, a flying pin accidentally strikes one ofclamping members 14, the grippers and 16 cannot be locked because,during the course of play, the solenoids 39 are not energized. The onlyeffect of such a pin would be to cause the momentary closing of switch43 which momentarily actuates the relay and thereby momentarily lightsthe lamp associated with the respotting units struck by the flying pin.If a suitable time delay is built into the relay, then such flying pinwill not even cause a momentary illumination of any of the lamps.

Whereas only a single embodiment has been illustrated, it will beapparent to those skilled in the art that many changes can be made bothin the details of construction and arrangement of parts withoutdeparting from the scope of the invention as defined in the appendedclaims.

What is claimed is:

1. In a bowling pin spotting machine, the combination of a plurality ofrespotting units for respotting bowling pins during a respotting cycleof the bowling pin spotting machine, each of said units comprising apair of grippers automatically self-operable to grip a standing pin,latch means alternately operative and inoperative for locking saidgrippers in engagement with a standing pin to enable said grippers topick up and to respot such pin, and means including an electromagnet foroperating said latch means; switch means operably connected forsimultaneously actuating all of said el'eotroinagnets; and timing meansoperative to actuate said switch means and thereby operate said latchmeans only during said respotting cycle.

2. In a bowling pin spotting machine, the combination of a plurality ofrespotting units movable through a plurality of cycles including arespotting cycle and a detecting cycle; indicating means operative toindicate which pins are standing; each of said respotting unitscomprising a pair of grippers adapted to grip a standing pinautomatically during said respotting cycle and said detecting cycle,latch means alternately operative and inoperative for locking saidgrippers in engagement with a standing pin gripped thereby, first meansfor actuating said latch means, and second means operably connected forautomatically actuating said indicating means in response to thepresence of a standing pin during both said respotting cycle and saiddetecting cycle; and means for controlling operation of said first meansto effect operation of said latch means only during said respottingcycle.

3. In a bowling pin spotting machine, the combination of a table; aplurality of respotting units carried by said table, each of said unitscomprising clamping means adapted to engage the head of a standing pinand clamp such pin against the pin deck whereby such pin arrestsdownward movement of said clamping means, said clamping means beingmounted so that when its downward movement is arrested, relativemovement occurs between it and said table, a pair of grippers adapted tomove into and away from gripping engagement with a standing pin inresponse to relative movement between said clamping means and saidtable, latch means for locking said grippers in engagement with astanding pin and automatically unlocking said grippers when such pin isrespotted, said latch means including a latch member and a detent, saiddetent being movable between operative and inoperative positions forengagement with said latch member, and means including an electromagnetfor moving said detent between said positions; switch means operablyconnected for simultaneously actuating all of said electromagnets; andtiming means operably connected for controlling operation of said switchmeans so that said grippers can be locked during predetermined portionsof the operation of the bowling pin spotting machine.

4. In a bowling pin spotting machine, the combination of a respottingtable; indicating means including a plurality of lamps operative toindicate which pins are standing; a plurality of respotting unitscarried by said table for movement through a plurality of cyclesincluding a respotting cycle for respotting standing pins and adetecting cycle merely for detecting the presence of standing pins, eachof said units comprising clamping means adapted to engage the head of astanding pin, means mounting said clamping means for movement relativeto said table upon engagement of said clamping means with a standingpin, a pair of grippers operatively connected for gripping a standingpin in response to said relative movement between said clamping meansand said table, latch means alternately operative and inoperative forlocking said gripping means in engagement with a standing pin, meansincluding an electromagnet operably connected for operating said latchmeans in response to actuation of said electromagnet, and first switchmeans operably connected for actuating one of said lamps in response tosaid relative movement between said clamping means and said table;second switch means operably connected for simultaneously actuating allof said electromagnets; and timing means operably connected foractuating said second switch means so that said latch means is operativeduring said respotting cycle and is inoperative at times including saiddetecting cycle other than during said respotting cycle.

5. A bowling pin spotting machine in accordance with claim 4 whereinsaid second switch means comprises a single-pole, single-throw switch.

6. A bowling pin spotting machine in accordance with claim 5 whereinsaid timing means includes a rotary cam operably connected for actuatingsaid switch, and a timing motor for driving said cam.

7. A bowling pin spotting machine in accordance with claim 6 whereineach of said first switch means comprises an electromagnetic relayhaving a set of contacts connected in series with the one of said lampsassociated therewith, and a single-pole switch operably connected toactuate said relay in response to said relative movement between saidclamping means and said table; said bowling pin spotting machine furtherincluding a single switch operably connected to all of said relays, anda rotary cam for actuating said single switch, said rotary cam beingdriven by said timing motor and operative to establish a hold circuitfor each of said relays during at least said detecting cycle.

8. In a bowling pinspotting machine, the combination of a plurality ofrespotting units for respotting standing pins during a respotting cycle;each of said units comprising gripping means responsive to engagementwith a bowling pin to be automatically self-closing about the pin, latchmeans adapted to be placed in operation to lock said gripping means inclosed position about said standing pin, and means operably connected tosaid latch means for placing the same in operation; and means forsimultaneously actuating all of said latch-operating means only duringsaid respotting cycle.

9. A bowling pinspotting machine in accordance with claim 8 wherein saidlast-recited means comprises timing motor means, and a bowlingball-operated pit switch for initiating operation of said timing motormeans at the start of the respotting cycle.

10. In a bowling pinspotting machine, the combination of a plurality ofrespotting units each comprising gripping means adapted to grip astanding pin automatically upon engagement therewith, latch meansalternately operative and inoperative for locking said gripping means inengagement with a standing pin, and an individual electromagnetic meansfor controlling the operation of said latch means; and a common controlmeans including switch means therein for simultaneously operating all ofsaid electromagnetic means to effect operation of said latch meansduring a limited period of time.

11. A bowling pinspotting machine in accordance with claim 10, includingcam means for operating said switch means, and timing motor means foroperating said cam means.

12. In a bowling pinspotting machine, the combination of a plurality ofrespotting units, means lowering and raising said plurality ofrespotting units successively immediately following the first ball in aframe to .detect, lift and respot standing pins and again immediatelyfollowing a second ball to detect and signal the presence of theremaining standing pins, each of said units compris- (a) gripping meansadapted to be closed automatically upon movement of the unit downwardlyinto engagement with a standing pin and thereafter to hold the pin uponupward movement,

(11) means in association with said gripping means for detecting andsignalling the presence of a pin engaged thereby,

(c) latch means directly operable on said gripping means and movable toan operative position in which the gripping means is held in a closedposition upon its engagement with a standing pin, and

(d) individual means controllable to place said latch means either insaid operative position or in an inoperative position in which thegripping and lifting of a standing pin is prevented,

and control means for the plurality of said individual means that arecontrollable to place said latch means in 8 operative and inoperativepositions, said control means effecting thereby the placement of eachsaid latch means in said operative position only immediately followingsaid first ball and in inoperative position during the actual rolling ofthe first and second balls against standing pins.

13. In a bowling pinspotting machine, the combination of a plurality ofrespotting units, means for lowering said plurality of respotting unitsto a predetermined lower level and raising the same to an inactive upperposition successively immediately following both the first and secondballs in a frame, each of said respotting units comprising:

(a) a jaw-type gripping means adapted to close about a standing pin andthereafter to hold the pin upon upward movement,

(b) a member normally operable by engagement with a pin upon movement ofthe respotting units fully to said lower level to move said jaw-typegripping means to a closed position,

(c) means associated with said gripping means for detecting andsignalling the presence of a pin therein,

(d) latch means directly operable on said gripping means and movable toan operative position in which the gripping means is held in said closedposition when moved thereto by the operation of said member, and

(e) individual means controllable to place said latch means either insaid operative position or in an inoperative position in which thegripping means is not held closed during upward movement thereof,

and common control means for the plurality of said individual means thatare controllable to place said latch means in operative and inoperativepositions, said control means effecting thereby the placement of eachsaid latch means in said operative position only during lowering andraising thereof immediately following rolling of said first ball and ininoperative position during the actual rolling of the first and secondballs against standing pins.

14. In a bowling pinspotting machine, the combination of a plurality ofrespotting units, means for lowering and raising said plurality ofrespotting units successively immediately following the first ball in aframe to detect, lift and respot standing pins and again immediatelyfollowing a second ball to detect the remaining standing pins, each ofsaid units comprising:

(a) jaw-type gripping means responsive to engagement with a bowling pinto be automatically self-closing about the pin and thereafter to holdthe pin in a raised position,

(b) means associated with said gripping means for detecting the presenceof a pin therein,

(c) a latch member engageable with a portion of said gripping means andmovable to an operative position in which the gripping means is held inclosed position after being closed by the action of a pin, and

(d) a solenoid operably associated with said latch member to controlmovement thereof between said operative position and an inoperativeposition in which the gripping means will not be held closed if engagedby a pin,

and a common electrical control system for operating the solenoidsassociated with the plurality of said latch members, said systemeffecting thereby the movement of said latch members to operativeposition only immediately following the rolling of said first ball andto an inoperative position during the actual rolling of the first andsecond balls against standing pins.

References Cited in the file of this patent UNITED STATES PATENTS2,559,274 Broekhuysen July 3, 1951 2,736,554 Fluke et al. Feb. 28, 19562,781,195 Holloway et al. Feb. 12, 1957 2,890,886 Dumas June 16, 19592,974,955 Walsh Mar. 14, 1961

1. IN A BOWLING PIN SPOTTING MACHINE, THE COMBINATION OF A PLURALITY OF RESPOTTING UNITS FOR RESPOTTING BOWLING PINS DURING A RESPOTTING CYCLE OF THE BOWLING PIN SPOTTING MACHINE, EACH OF SAID UNITS COMPRISING A PAIR OF GRIPPERS AUTOMATICALLY SELF-OPERABLE TO GRIP A STANDING PIN, LATCH MEANS ALTERNATELY OPERATIVE AND INOPERATIVE FOR LOCKING SAID GRIPPERS IN ENGAGEMENT WITH A STANDING PIN TO ENABLE SAID GRIPPERS TO PICK UP AND TO RESPOT SUCH PIN, AND MEANS INCLUDING AN ELECTROMAGNET FOR OPERATING SAID LATCH MEANS; SWITCH MEANS OPERABLY CONNECTED FOR SIMULTANEOUSLY ACTUATING ALL OF SAID ELECTROMAGNETS; AND TIMING MEANS OPERATIVE TO ACTUATE SAID SWITCH MEANS AND THEREBY OPERATE SAID LATCH MEANS ONLY DURING SAID RESPOTTING CYCLE. 